Magnesium tennis racket with weighted throat piece

ABSTRACT

The invention is a novel configuration of a metal tennis racket characterized by an extruded magnesium frame substantially Ishaped in cross section, and having inside and outside channels. A molded grommetted string cushion strip seats in the outside channel of the bow of the frame insulating the strings from all metal contact. An inverted U-shaped element bridges the throat of the racket completing the bow and seats in the interior channel of the frame for added structural support. A separate grommetted string cushion element seats along the bridge and features a recess therein which receives balancing slugs of different weights enabling adjustment in weight and balance of the racket prior to stringing.

United States Patent Wilkens 51 Feb. 15, 1972 MAGNESIUM TENNIS RACKETWITH WEIGHTED THROAT PIECE FOREIGN PATENTS OR APPLICATIONS 224,724 11/1924 Great Britain ..273/73 H 72 Inventor: Howard John Wilkens, 8720Woodview 488,738 "1930 Germany Drive Cincinnati, Ohio 45231 252,4806/]926 Great Bntam ..273/73 H Filed! 1970 Primary Examiner-Richard C.Pinkham Assistant ExaminerRichard J. Apley 1 Appl' 7457 Attorney-DonaldS. Olexa, Jerome M. Teplitz, John G. Heimovics, William G. Lawler, Jrand Hofgren, Wegner, Al-

[52] US. Cl. ..273/73 G, 273/73 C, 273/73 D, Stellman a d COId 273/73 H[511 1m. 01. ..A63b 49/04 1 1 ABSTRACT [58] new of Search The inventionis a novel configuration of a metal tennis racket characterized by anextruded magnesium frame substantially References Cited l-shaped incross section, and having inside and outside channels. A moldedgrommetted string cushion strip seats in the UNITED STATES PATENTSoutside channel of the bow of the frame insulating the strings 1,452,8034/1923 Harris ..273/73 H from metal Contact An inverted P elementbridges 1,937,787 12/1933 Robinson H the throat of the racket completmgthe bow and seats m the m- 2,171 223 8/1939 Robinson... ..273/73 Hchannel 0f the frame added mural PP A 2 742'289 4/1956 Anward 273/73 Hseparate grommetted string cushion element seats along the bridge andfeatures a recess therein which receives balancing 3,540,728 11/1970Palmer ..273/73 J Slugs of different weights enabling adjustment inweight and balance of the racket prior to stringing.

2 Claims, 10 Drawing Figures 2a 3 I I l I 7 W}; 1: WI I l l1 l l l I f 1cpl I z i I 21 I 2 WEIGHTED SLUG l HIEIHI.

MAGNESIUM TENNIS RACKET WITH WEIGIITED THROAT PIECE BACKGROUND Thisinvention is in the field of sports rackets and specifically relates tothe construction of a tennis racket having a frame of unique designwhich incorporates a resilient string cushion member and means to changethe weight and balance of the racket.

Over the past several years, metal tennis rackets of varying designshave been circulated on the marketand have experienced a degree ofacceptance. However, these rackets have exhibited shortcomings which itis a purpose of this invention to overcome. For example, rackets madewith a steel frame have been found to be too flexible. The player isrequired to adjust his sense of timing to this added flexibility, andsome feel that they do not have the same control over the ball as theyhave with the conventional wood racket. There have also been reports ofrusting of the steel frames.

Other rackets have been manufactured with aluminum frames. These racketshave been found to be extremely stiff and suprisingly heavy. While someplayers appear to like this added firmness, a racket having a weight andflexibility similar to that of wood rackets is generally preferred.

Another problem encountered with metal rackets is in the stringing. Ithas been found that many of these rackets cannot be restrung onconventional stringing machines without a special adapter, and that theunorthodox manner of stringing requires additional time to complete thejob. Reports of string breakage after a short time in play are common,causing the manufacturers to seek various methods of protecting thestrings from the sharp metal edges of the racket holes. One approach tothis problem was to provide individual plastic grommets inserted intoeach string hole. These grommets had to be of different diameters andlengths to accommodate single or double thicknesses of string andvariation in the thickness of the bow and the throat sections. Theseindividual grommets were difficult to handle in that they tended to fallout leaving the purchaser of the unstrung racket with the problem ofdetermining which grommet went into which hole. In addition, theindividual plastic grommets often cracked and became effective. A bettersolution to the problem of breaking strings was suggested in US. Pat.No, 2,742,289, which broadly taught the placing of a molded plasticstrip in a channel around the outside of the racket bow, with integralgrommets or sleeves extending through the holes of the bow.

It is a purpose of this invention to improve upon the aforementionedstring cushion and to overcome the aforementioned objections to anddifficulties with metal tennis rackets in general. Accordingly, oneobjective of the invention is to provide a metal racket having aselected weight and flexibility, including weight and flexibilitycombinations substantially matching those of wooden rackets. A furtherobjective of the invention is to provide a racket which can be strungand restrung in the conventional manner and on conventional stringingmachines without the need foe special adapters. Another objective ofthis invention is to provide a racket frame structure which includesmeans for adjusting the weight and balance of the racket to suit theuser.

Still another objective of this invention is to provide a unique throatconstruction for the frame which particularly resists twist anddistortion of the frame structure during stringing and in play.

A still further objection of the invention is to include means which inconjunction with the string insulating means across the bridge section,accepts elements of varying specific gravity to change the weight of theracket.

It is an additional objective of this invention to provide a racketwhich meets all the aforementioned objectives and having an extrudedframe.

SUMMARY Basically, the invention is a tennis racket comprising ametallic frame of generally l-shaped cross section, which frame has afirst channel in its exterior face thereof and a second and like channelin its interior face. A central portion of the frame is bent into aconventional bow across which the strings of the racket are strung,while the end portions of the frame extend outwardly from the bow inparallel forming the stock of the racket to which the handle isattached. A throat bridge comprised of a generally U-shaped elementcloses the throat of the bow; said bridge having a plurality oflaterally extending tongues which ride snugly within the interiorchannel of the frame, and are selectively located to brace the frameagainst twist. A combination string cushion and weight adjustment means,disposed along that portion of the throat bridge which closes the bow,cushions the strings passing therethrough and provides a recess for thereception of weighting elements of selected density by which the swingweight and balance of the racket may be adjusted prior to stringing.Grip means adopted to receive therein the ends of said parallel frameelements forms the handle of the racket.

The invention as described overcomes the difficulties previouslyencountered with metal rackets. It can be strunglike a wood'racket, hasthe advantages of lightness in weight, and a flexibility substantiallythe same as that of a wood racket; yet it will not rust, has greatdimensional stability, and provides for weight adjustment to suit theuser.

Other objectives, advantages, and various further features of noveltyand invention will be pointed out or will occur to those skilled in theart from a reading of the following specification in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a tennisracket of the invention.

FIG. 2 is a cross-sectional view of a portion of the throat section ofthe racket taken along line 22 of FIG. 1.

FIG. 3 is a cross-sectional view of a portion of the throat section ofthe racket taken along line 33 of FIG. 1.

FIG. 4 is a cross-sectional view of the bow of the racket taken alongline 4-4 of FIG. 1.

FIG. 5 is a cutaway plan view of a portion of the bow of the rackettaken along line 5-5 of FIG. 1.

FIG. 6 (a), (b), (c), is an exploded view, partially in cross section,of the center portion of the throat bridge of the racket illustrated inFIG. 1.

FIG. 7 is a cross-sectional view of the throat of a racket of theinvention taken along line 77 of FIG. 1.

FIG. 8 is a top view of a throat bridge string cushion and weightreceiving element of the invention illustrated in FIG. 6 (0).

FIG. 9 is a cross-sectional view of the handle and grip portion of theracket taken along line 9-9 of FIG. 1.

FIG. 10 is a plan view of a throat bridge of the invention incorporatedin the racket of FIG. 1.

DETAIL DESCRIPTION OF THE INVENTION Invention is an improved tennisracket, the various features of which will be described in connectionwith the drawings. Principal among these improvements is the shape andstructure of the frame, best illustrated in FIG. 1, 2, 3, and 4.

The frame may be made of any suitable metal material; however, it hasbeen found most advantageous to extrude the frame of a magnesium alloysuch as ZK60. The extruded frame element 1 is l-shaped, forming aninside channel 2 and an outside channel 3 (See Fig. 2). Channel 2 isessentially a dovetailed groove, having sides which taper away from theopen top of the groove to a wider flat base 2a. Channel 3 is similar tochannel 2 except that the sidewalls thereof comprise a first taperedsection 3a communicating with the opening of the groove and an innersection 3b standing perpendicular to the base 30 of the channel. FIG. 4includes the general exterior dimensions of a frame of the inventionconsistent with the objective of the invention.

Channel 3 is shaped to retain therein a shaped resilient, grommettedstring cushion strip 4. String cushion 4 is preferably made of anysuitable resilient plastic such as nylon and is molded to substantiallyfill channel 3. Strip 4 has spaced grommets 4b integrally moldedtherein, which grommets fit snugly into string holes in the bow 1 (SeeFig. 5). In addition, strip 4 has string recesses 40 therein whichpermit the strings to ride inside the outer perphiry of the bow andenjoy the protection of the surrounding materials of strip 4 andframe 1. Strip 4 is forced into channel 2 where the angled sides 3aserve to retain strip 4 in place, greatly facilitating stringing of theracket.

Particularly unique to the invention is the throat bridge 7 of theracket. Frame 1 is bent into the general racket shape illustrated inFIG. 1, forming a bow 6 and a stock and handle section 14. Sharp bendsin the frame 1 are avoided by gentlyv curving the ends 8 and 9 outwardlyfrom the bow 6 into a parallel disposition forming the stock 14. Thecircular string section of the racket, designated generally 6a, is thenclosed by a throat bridge element 7 illustrated in FIG. 1 and 10. Bridge7 is an extruded or machined piece having a top section 10 and twoopposing legs 11 and 12. Bridge 7 seats in the throat of the frame .Iwith sectionl0 extending across the open throat of frame 1 closing thebow of the racket and establishing itsstring support area 6. Legs 11 and12 extend down along the inside of frame legs 8 and 9 and are riveted tothe frame 1 of the racket by rivets I3.

Referring to FIGS. 10, 2 and 3, legs 11 and 12 are provided with tongues11a and 12a which extend laterally from the sides thereof and fit snuglyinto interior channel 2 ofthe frame when bridge 7 is seated in thethroat of the racket. The remainder of legs 11 and 12 are too large tofit within channel 2 and ride outside thereof and against the insideedges of frame 1. In this embodiment of the invention tongues 11a and12a do not extend for the entire length of legs 8 and 9; but extendinwardly from the extremities thereof only approximately one-third ofthe length of each leg. This construction provides four distinct areasof lateral support for frame 1, and leaves open the portion of channel 2therebetween into which balancing weight elements may be inserted ifdesired. The racket may be made more rigid and twist resistant byextending tongues 11a and 120 along the entire length oflegs 8 and 9respectively.

The stock 14 of the racket is formed by the extremities 8 and 9 of frame1 which extend in parallel from the bow 6. Below the throat bridge 7 andin the area of the handle 15 of the racket, sections 8 and 9 are heldtogether by spacing braces 17 and 17a the ends of which also ride snuglywithin interior channel 2 and which are held in place by through rivetsl8 and 19(See FIGS. 1 and 9).

Referring to FIG. 9, the handle 15 of the racket is comprised of twomolded halves 15a and 15b which ride between and over the tops andbottoms of legs 8 and 9. The handle is preferably made of molded plasticmaterial such as Cycolac, but may be made of any material which willwithstand the stresses encountered in play. The inserted handle pieces15a and 15b are then wrapped with a suitable material to fonn aconventional grip 16 for the racket.

Another particularly unique feature of the invention is in theconstruction of a weight retaining throat string cushion 20 which seatsin a recess 21 in the throat bridge 7 and provides for the installationfor a weighted slug 22 in the throat area. Cushion 20 functions in themanner of grommet 4 to protect the strings of the racket from abrasionagainst the metal bridge 7 in that it is comprised of grommets 24 whichfit into string holes 25 in bridge element 10(See FIG. 6).

Referring to FIGS. 6, 7, 8 and 10. cushion strip 20 has a rectangularbase 23, and a rectangular recess 26 therein the purpose of which is toaccommodate a weighting slug 22 of chosen density. Slug 22 is sized tofit within recess 26 and has holes 28 therein to provide for the assa etherethrou h of grommets 24. FIGS. 6 (a (b), and c) il ustrate the reative positions of bridge element 10, cushion strip 20, and weightingslug 22. FIG. 7 illustrates steps 30 and 31 cut into the edges of bridgeelement 10, which steps receive the outside edges 32 and 33 of strip 20in an overlapping relationship, so that upon assembly slug 22 iscompletely enclosed between bridge element l0 and cushion strip 20.

Weight of the slug 22 is varied by making it from a chosen variety ofmaterials of different density, such as: lead for a heavy racket, zincfor a medium weight, and polyethylene for light weight. All of the slugsare the same size to prevent string cushion 20 from collapsing duringstringing.

During the development of this invention it was found that not allmagnesium alloys could be used. When magnesium alloy No. AZ3l was tried,for instance, the frame pulled out of shape during the stringingoperation, and became further deformed in about 2 hours of actual play.This problem was overcome by employing magnesium alloy No. ZK60. Withthe use of alloy ZK6O the forementioned deformations did not reoccur.Field tests were conducted on aluminum, steel and wood rackets of priorart construction to test the rigidity of these rackets. It was foundthat under a 40-pound load, the tip of the bow of a steelracket'deflected l.75 inches, the tip of the aluminum racket deflected0.95 inches, and two representative wood frame rackets deflected 1.35inches. It was observed from this test that variations in flexibilitybetween the wooden and prior art metal rackets was more thanpsychological reaction to the feel to the metal rackets and that a needexisted for a metal racket having a flex equivalent to that to whichplayers have become accustomed, or a flex which could be tailored to thelikes of the individual.

By varying the cross-sectional area of the frame 1, with due regard foroverall strength, and the length of tongues 11 a, b and 12 a, b, withrespect to legs 11 and 12, rackets having more or less flexibility canbe produced; including flexes comparable to conventional wooden rackets.

While the principles of the invention have been described in connectionwith the above specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationsto the scope of the invention as set forth in the accompanying claims.

I claim:

1. A tennis racket or the like comprising a frame having an open throat,throat bridge means adapted to fit within and close said open throatand, balancing means attaching to said bridge means to vary the weightand balance of said racket, said balancing means comprising a stringcushion fitted to said throat bridge, and a weighted slug of preselectedweight and density, said string cushion having a recess therein and saidslug being adapted to fit within said recess.

2. The device of claim 1 wherein said throat bridge means comprises aportion of the bow of said tennis racket having holes therein for thepassage of the racket strings, said string cushion includes grommetsextending therefrom and passing through the string holes in said throatbridge, and said slug has holes therein adapted to permit passage ofsaid grommets therethrough when said slug is fitted within said recess.

* at a:

1. A tennis racket or the like comprising a frame having an open throat,throat bridge means adapted to fit within and close said open throatand, balancing means attaching to said bridge means to vary the weightand balance of said racket, said balancing means comprising a stringcushion fitted to said throat bridge, and a weighted slug of preselectedweight and density, said string cushion having a recess therein and saidslug being adapted to fit within said recess.
 2. The device of claim 1wherein said throat bridge means comprises a portion of the bow of saidtennis racket having holes therein for the passage of the racketstrings, said string cushion includes grommets extending therefrom andpassing through the string holes in said throat bridge, and said slughas holes therein adapted to permit passage of said grommetstherethrough when said slug is fitted within said recess.